Method for controlling a reactive sputtering process

Abstract

A method is proposed for controlling a reactive sputtering process wherein the working point on the physical characteristic curves, cathode voltage or working current intensity over reactive gas flow to the sputtering apparatus, defined by the value of one of the two factors determining the electrical power drain of the reactive sputtering process, is adjusted and maintained constant by metering the reactive gas, for example O 2 , to the process chamber. Further, the invention proposes a device for the practice of the method, wherein a sputtering apparatus is provided, comprising a controller 5 (reactive gas controller) and a control valve 8 for metering the reactive gas. Further, a signal line 15 is provided which carries the cathode voltage to the input of the controller in which the output of the controller is connected to the control valve via a line 16 which supplies the adjusting magnitude computed in the controller to the control valve.

I claim: 
     
       1. Method for controlling a reactive sputtering process comprising providing a cathode bearing a target to be sputtered in an evacuable chamber,   supplying reactive gas to said chamber for reactive sputtering said target to produce a layer comprising a chemical compound having a metallic component, said layer emitting secondary electrons during sputtering,   reactively sputtering said target by connecting said cathode to a power supply for producing a cathode discharge voltage V and a cathode discharge current I,   keeping power P=IV constant, thereby providing a physical characteristic curve of discharge voltage versus reactive gas flow having an overall slope and a working portion on which a desired working voltage is located, said working portion having a slope of opposite sign than said overall slope,   decreasing the reactive gas flow when said physical characteristic curve dictates increasing said reactive gas flow to achieve said desired working voltage, and   increasing the reactive gas flow when said physical characteristic curve dictates decreasing said reactive gas flow to achieve said desired working voltage.   
     
     
       2. Method as in claim 1 wherein said chemical compound has a yield of secondary electrons during sputtering that is higher than that of said metallic component, whereby said physical characteristic curve has an overall slope which is negative and a working portion with a slope which is positive. 
     
     
       3. Method as in claim 2 wherein said chemical compound is one of Al 2  O 3  and SiO 2 . 
     
     
       4. Method as in claim 1 wherein said chemical compound has a yield of secondary electrons during sputtering that is lower than that of said metallic component, whereby said physical characteristic curve has an overall slope which is positive and a working portion with a slope which is negative. 
     
     
       5. Method as in claim 4 wherein said chemical compound is CrO. 
     
     
       6. Method for controlling a reactive sputtering process comprising providing a cathode bearing a target to be sputtered,   supplying reactive gas to said chamber for reactive sputtering said target to produce a layer comprising a chemical compound having a metallic component, said layer emitting secondary electrons during sputtering,   reactively sputtering said target by connecting said cathode to a power supply for producing a cathode discharge voltage V and a cathode discharge current I,   keeping power P=IV constant, thereby producing a physical characteristic curve of discharge current versus reactive gas flow having an overall slope and a working portion on which a desired working current is located, said working portion having a slope of opposite sign than said overall slope,   increasing the reactive gas flow when said physical characteristic curve dictates decreasing said reactive gas flow to achieve said desired working current, and   decreasing the reactive gas flow when said physical characteristic curve dictates increasing said reactive gas flow to achieve said desire working current.   
     
     
       7. Method as in claim 6 wherein said chemical compound has a yield of secondary electrons during sputtering that is higher than that of said metallic component, whereby said physical characteristic curve has an overall slope which is positive and a working portion with a slope which is negative. 
     
     
       8. Method as in claim 7 wherein said chemical compound is one of Al 2  O 3  and SiO 2 . 
     
     
       9. Method as in claim 6 wherein said chemical compound has a yield of secondary electrons during sputtering that is lower than said metallic component, whereby said physical characteristic curve has an overall slope which is negative and a working portion with a slope which is positive. 
     
     
       10. Method as in claim 9 wherein said chemical compound is CrO.